It depends what you mean by nice ambience and good food. Do you want elegant and upscale? Comfortable and accessible? Either way, if you only have time for one meal, be sure to go to the downtown (outdoor pedestrian) mall. It's the heart of the action, and very charming.

the downtown mall is charming but i've personally had lousy luck with food there. admittedly i'm not a local - just visit a lot from richmond. so maybe i just order wrong. :)i like maya in charlottesville. i know they do a brunch that's delicious (the vegetable potato cakes with smoked salmon are to die for) but i don't know about lunch. not far from the mall.